In the construction of buildings with flat roofs, especially commercial buildings, a blocking system of some type is typically provided about the perimeter edge of the roof structure to act as a border for and to facilitate securement of any of various roofing elements that may commonly be utilized. For example, many conventional commercial buildings are constructed with flat roofs on which a lightweight concrete or a comparable synthetic flowable cementitious roofing material may be cast in situ. Other commercial building roofs may utilize rigid insulation boards or panels which may be made of wood fiber, perlite, polyisocyanurate, polystyrene (expanded or extruded), cellular glass, gypsum board, and composites. A perimeter edge blocking system provides a containment border within which the roofing material is contained while being installed. The perimeter edge blocking system may also provide for the securement of other roofing elements, such as gravel stops, roof curbs, copings, fascia, etc.
Conventionally, roof blocking systems are fabricated of elongate wood boards nailed to the roof structure. However, wood roof blocking systems suffer several disadvantages. Wood is subject to deterioration and decay from exposure over time to the elements, particularly moisture, even when treated with preservatives. Wood also may be damaged by insects such as termites. In addition, variations commonly occur from one wood board to another due to natural physical differences in grain, knots, splintering and splitting, and wood boards are subject to warping, all of which may result in undesirable dimensional variations between differing wood boards.
All of these reasons as well as other factors make wood a less than optimal material from which to fabricate roof blocking systems. Accordingly, a need exists in the construction industry for a new form of roof blocking system made of material other than wood which will overcome the above-described problems. U.S. Pat. No. 6,237,293 proposes a roof blocking system which may be made of galvanized steel, other steel, aluminum or plastic. Alternative Roof Blocking System, located in Fort Lauderdale, Fla., produces a commercial embodiment of such roof blocking system identified by the designation “A.R.B.S.” which is intended as a substitute for wood blocking systems. While the “A.R.B.S.” system performs adequately for its intended purpose, the system is fabricated in a unitary one-piece configuration, which makes the system somewhat difficult to handle and to install.